Tesh are those with super or preternatural ability, not unlike the natural witches of Asiri Asa. Tesh are usually a mix of Marcwith's families. Unlike witches, which are products of humans, Tesh are not born with barriers between the twin worlds and none of their personal ability is put forward to creating these barriers; abilities are inherit, obvious, and completely controlled. The comfortable relationship with the supernatural in Marcwith is often attributed to the continents greater observance to religious ceremony, which allows Tesh to act as 'gateways' rather than solid walls or open doors. They are known to be much more ritualized, using tools such as środek to enhance their abilities.
Unlike natural witches, Tesh families do not see any value in entities and little value in ghosts, so there are much fewer mediums, in fact much fewer passive powers in general. They mostly deal with curses – some curses are inherited, some not, but that’s the main job of any Tesh working within the supernatural. Because of the upkeep of most traditions, Marcwith isn’t plagued by as many hauntings as Asiri Asa would be. As generations have merged with humans, more barriers have formed, and some Tesh will develop no abilities at all.